import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleep

def get_number_aliens_x(ai_settings,alien_width):
    available_space_x=ai_settings.screen_width-2* alien_width
    number_alien_x=int(available_space_x/(2*alien_width))
    return number_alien_x

def get_number_rows(ai_settings,ship_height,alien_height):
    available_space_y=ai_settings.screen_height-3*alien_height-ship_height
    number_rows=int(available_space_y/(2*alien_height))
    return number_rows

def creat_alien(ai_settings,screen,aliens,alien_number,row_number):
    alien = Alien(ai_settings, screen)
    alien_width = alien.rect.width
    # for alien_number in range(number_alien_x):
    #     alien=Alien(ai_settings,screen)
    alien.x=alien_width+ 2*alien_width * alien_number
    alien.rect.x=alien.x
    alien.rect.y = alien.rect.height + 2 * alien.rect.height * row_number
    aliens.add(alien)

def creat_fleet(ai_settings,screen,ship,aliens):
    alien=Alien(ai_settings,screen)
    number_aliens_x=get_number_aliens_x(ai_settings,alien.rect.width)
    number_rows=get_number_rows(ai_settings,ship.rect.height,alien.rect.height)

    for row_number in range(number_rows):
        for alien_number in range(number_aliens_x):
            creat_alien(ai_settings,screen,aliens,alien_number,row_number)

def first_bullet(ai_settings,screen,ship,bullets):
    if len(bullets) <= ai_settings.bullets_allowed:
        new_bullet = Bullet(ai_settings, screen, ship)
        bullets.add(new_bullet)

def check_keydown_events(event,ai_settings,screen,ship,bullets):
    if event.key==pygame.K_RIGHT:
        ship.moving_right=True
    elif event.key==pygame.K_LEFT:
        ship.moving_left=True
    elif event.key==pygame.K_UP:
        ship.moving_up=True
    elif event.key==pygame.K_DOWN:
        ship.moving_down=True
    elif event.key==pygame.K_SPACE:
        first_bullet(ai_settings,screen,ship,bullets)
    elif event.key == pygame.K_q:
        sys.exit()


def check_keyup_events(event,ship):
    if event.key==pygame.K_RIGHT:
        ship.moving_right=False
    elif event.key==pygame.K_LEFT:
        ship.moving_left=False
    elif event.key==pygame.K_UP:
        ship.moving_up=False
    elif event.key==pygame.K_DOWN:
        ship.moving_down=False


def check_events(ai_settings,screen,stats,sb,
                      play_button,ship, aliens,bullets):
    """响应按键和鼠标事件"""
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()
        elif event.type==pygame.KEYDOWN:
            check_keydown_events(event,ai_settings,screen,ship,bullets)
        elif event.type==pygame.KEYUP:
            check_keyup_events(event, ship)
        elif event.type==pygame.MOUSEBUTTONDOWN:
            mouse_x,mouse_y=pygame.mouse.get_pos()
            check_play_button(ai_settings,screen,stats,sb,
                      play_button,ship, aliens,bullets,mouse_x,mouse_y)

def check_play_button(ai_settings,screen,stats,sb,
         play_button,ship, aliens,bullets,mouse_x,mouse_y):
    button_clicked= play_button.rect.collidepoint(mouse_x,mouse_y)
    if button_clicked and not stats.game_active:
        ai_settings.initialize_dynamic_settings()
        pygame.mouse.set_visible(False)
        #重置游戏统计信息
        stats.reset_stats()
        stats.game_active=True
        #重置记分牌图像
        sb.prep_score()
        # sb.prep_high_score()
        sb.prep_level()
        sb.prep_ships()
        #清空外星人列表和子弹列表
        aliens.empty()
        bullets.empty()

        creat_fleet(ai_settings,screen,ship,aliens)
        ship.center_ship()

def update_screen(ai_settings,screen,stats,sb,ship,aliens,bullets,play_button):
    """更新屏幕上的图像，并切换到新屏幕"""
    # 每次循环时都重绘屏幕
    screen.fill(ai_settings.bg_color)
    #显示得分
    sb.show_score()
    for bullet in bullets.sprites():
        bullet.draw_bullet()
    ship.blitme()
    aliens.draw(screen)

    #如果游戏处于非活动状态，绘制Play按钮
    if not stats.game_active:
        play_button.draw_button()
    # 让最近绘制的屏幕可见
    pygame.display.flip()


def update_bullets(ai_settings,screen,stats,sb,ship,aliens,bullets):
    """更新子弹的位置，并删除已消失的子弹"""
    # 更新子弹的位置
    bullets.update()
    # 删除已消失的子弹
    for bullet in bullets.copy():
        if bullet.rect.bottom <= 0:
        # if bullet.rect.right >ai_settings.screen_width:
            bullets.remove(bullet)
    check_bullet_alien_collsions(ai_settings,screen,stats,sb,ship,aliens,bullets)

def check_bullet_alien_collsions(ai_settings,screen,stats,sb,ship,aliens,bullets):
    collisions=pygame.sprite.groupcollide(bullets,aliens,True,True)
    if collisions:
        for aliens in collisions.values():
            stats.score+=ai_settings.alien_points*len(aliens)
            sb.prep_score()
        check_high_score(stats,sb)
    if len(aliens)==0:
        bullets.empty()
        ai_settings.increase_speed()
        stats.level+=1
        sb.prep_level()
        creat_fleet(ai_settings, screen, ship, aliens)

def check_fleet_edges(ai_settings, aliens):
    """有外星人到达边缘时采取相应的措施"""
    for alien in aliens.sprites():
        if alien.check_edges():
            change_fleet_direction(ai_settings, aliens)
            break

def change_fleet_direction(ai_settings, aliens):
    """将整群外星人下移，并改变它们的方向"""
    for alien in aliens.sprites():
        alien.rect.y += ai_settings.fleet_drop_speed
    ai_settings.fleet_direction *= -1

def ship_hit(ai_settings,screen,stats,sb,ship,aliens,bullets):
    if stats.ships_left>0:
        stats.ships_left-=1
        sb.prep_ships()
        aliens.empty()
        bullets.empty()

        creat_fleet(ai_settings,screen,ship,aliens)
        ship.center_ship()
        sleep(0.5)
    else:
        stats.game_active=False
        pygame.mouse.set_visible(True)
def check_aliens_bottom(ai_settings, screen, stats, sb, ship, aliens,bullets):
    """检查是否有外星人到达了屏幕底端"""
    screen_rect = screen.get_rect()
    for alien in aliens.sprites():
        if alien.rect.bottom >= screen_rect.bottom:
            # 像飞船被撞到一样进行处理
            ship_hit(ai_settings,screen, stats,sb, ship, aliens, bullets)
            break

def update_aliens(ai_settings,screen, stats, sb, ship, aliens, bullets):
    """
    检查是否有外星人位于屏幕边缘，并更新整群外星人的位置
    """
    check_fleet_edges(ai_settings, aliens)
    check_aliens_bottom(ai_settings,screen, stats, sb, ship, aliens, bullets)
    aliens.update()

    if pygame.sprite.spritecollideany(ship,aliens):
        # print("Ship hit!!!")
        ship_hit(ai_settings,screen,stats,sb,ship,aliens,bullets)

def check_high_score(stats, sb):
    """检查是否诞生了新的最高得分"""
    if stats.score > stats.high_score:
        stats.high_score = stats.score
        sb.prep_high_score()
